So to get back on topic

, I am planning on doing the same thing as Deluge; playing FF games on Pandora emulators in a semi-legit manner. Semi-legit meaning I own a physical original copy/re-release of the game so I can justify downloading the ROM.
@Deluge turns our that your reason for wanting a DS emulator is null. FF4 was actually re-released for the PSX after all, the game was released under the name of
Final Fantasy Chronicles and was bundled with the best RPG in existence (IMO) Chrono Trigger! Both games were released with new anime/CG cut scenes. So you can own a legit copy of this game and emulate on the Pandora PSX emulator after all.
You could alternately go on ebay and buy the original game for the SNES and get d/l the SNES ROM for it, but just a warning the SNES FF games go for $40+ cause of their popularity. I suggest trying to find the PSX versions.
All we have to do now is wait patiently for the PSP emulator to be optimized to play Crisis Core on the Pandora.........maybe one day! By the way, if you haven't played FF7CC yet I suggest borrowing a PSP and game from someone, it is well worth it.